51 Collectable Model Trains: Maintenance Tips: I have trouble with my locos reversing properly.
Description
This article is from the Model Trains FAQ, by Christopher D Coleman with numerous contributions by others.
51 Collectable Model Trains: Maintenance Tips: I have trouble with my locos reversing properly.
A sequencer is the device that controls locomotive direction. The
"E-Unit" was originally developed by Ives. It was a trademarked name I
believe, where the generic name for the device is a sequencer. When
Ives went bankrupt in 1931 Lionel bought it principally to acquire
it's superior sequencer. Until then Lionel had used a simpler and less
reliable two position sequencer. Ives' was the three position seen in
'modern' tinplate locos. During it's classic era Lionel designated
locos with E-units as -E such as the 300E and 700E. Flyer never owned
the right to use the name E-unit specifically, but their sequencer is
the same principal interpreted differently. I believe the E stood for
Electronic unit. Although it wasn't really electronic by today's
standards, it must have seemed that way in those times before
transistors, and vacuum tubes were the cutting edge.
Most sequencers work by means of a rotating drum and contact fingers.
The drum has copper contacts on its surface arranged so that there
will be connections made between different fingers for different
positions of the drum. The circuitry of this is explained in MOTOR
DESIGN. An electric coil plunger engages a series of teeth on the drum
and pulls it a fraction of a rotation each time the coil is energized.
The most common problem with sequencers is a lack of proper contact
between fingers and drum, or a failure of the coil to properly
position the drum. The contacts are best cleaned with Zero Residue or
TV Tuner spray cleaner. If this fails you may carefully clean the drum
in place with an eraser. Be careful not to touch the contact fingers.
THEY ARE VERY DELICATE so BE CAREFUL. If the drum is pitted or damaged
it needs to be replaced. Disassembling a sequencer is VERY tricky and
delicate. For Lionel units the sides of the unit must be forced apart
to remove the drum, and a pair of external snap ring pliers are good
for this. The drum and finger assemblies will pop out. When
reassembling press the assembly together by hand first and gently
finish it in a vice. If the fingers are damaged it may be possible to
re-bend them with precision pliers, but replacement is the best
option. If your coil plunger is sticking do not oil it! The oil will
"clog" it up. A pipe cleaner is useful here to clean the interior of
the coil, as is spray cleaner. When the interior is clean, the plunger
should slide easily. If not, the coil case is likely warped, so
replacing the unit is the best solution. This same procedure may be
used for accessories using the coil plunger system, such as crossing
gates.
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